Weird Inspiron 15 7590 2in1 performance issues (incl. ThrottleStop saga)

[CompuNerd2K]

I've had this laptop (i7-8565U + MX250 + 4K IPS variant) since August 2019. For the first several months it was absolutely great, working just fine even for games and all that jazz. Then a BIOS update hit in March which first caused my fans and thermals to go completely out of whack, and then it went into some weird state which was worsened performance to keep it cool. Sadly, even after a fan replacement (yeah, fan lasted barely over a year before a clip broke off the motherboard area and got into the fan, killing it) and a fresh application of Arctic Silver 5 by a local computer shop (I can't fix modern thin laptops myself, sadly) the system was slow and it was just getting worse. The repaste didn't fix the issue with the CPU going down as low as 400Mhz for no reason while the GPU was going at full-on boost clocks. Plus, the CB R15 score was barely in the lower 400s whether I was plugged in or not. Then I managed to fix the low Cinebench and sluggish response (but not the GPU-induced throttling) issue with ThrottleStop and some BIOS settings. Here is where I noticed the first oddity. When I unplug the charger, it holds high power levels just fine (I removed the power limits and undervolted, among other things) for a very short time, but then it falls down to the stock TDP of 15W and 0.7-1GHz reduction in under-load turbo clocks when running a stress test. For example, on charger I idle at 4090Mhz, the when a stress test settles it at around 3600Mhz, shortly after I pull the charger it falls to the 2600MHz ballpark. Connecting the charger makes the power soar up to 30+W and the temp goes from 73C to the PROCHOT 100C limit w/ full speed. Is there a way to override this battery power limit which from what I have read in other posts is imposed by the disgusting EC chip (I already have a tool that kills the EC fan control and lets me crank it to max)? One thing of note is that when I reinstalled Windows from the recovery partition due to a bad update crashing my previous setup, it seems that my changes in ThrottleStop result in peaks of 10W more than before (so basically it can go shortly up as high as ~42W but reduces by a few due to thermal and ring EDP OTHER constraints) giving me an extra 100+ points on CB R15. Thinking this was old drivers being plain better, I killed Windows Update and removed all the Dell SupportAssist and Dell Update junkware and forced a manual upgrade to 20H2 as the 1809 from the recovery partition has security flaws) and so far so good. So in summary, I need two things fixed to take advantage of my otherwise perfect ThrottleStop setup. Firstly, as stated above, how do I make it (if possible) perform without power restrictions on battery like it does on the charger, and secondly how do I override that BIO updated induced issue where the CPU throttles to useless speeds if a game or other program makes both it and the GPU draw significant power (this was present before I ever tweaked anything and ThrottleStop had no effect). Downgrading the BIOS doesn't work because the updates were supposedly "security advisory" updates (yeah right, more like a nice and very pathetic try at planned obsolescence that I remedied, at least for CPU-only stuff, with ThrottleStop). The reason I so desperately need the battery performance fixed is so I can use this thing full-tilt when flying (not all planes have power outlets to feed my power-unleashed beast). No need to hurry with the answer as I have a beefy desktop as my main computer so I can wait for anything regarding the laptop. If it matters, current Cinebench R15 scores are in the mid-to-high 700s with occasional spikes and dips to low 800s or low 700s respectively depending on how warm the laptop is.